Typical fields of usage of heat pumps are to cool a region to be cooled and/or to heat a region to be heated. A heat pump typically consisting of an evaporator, a compressor and a condenser comprises, for this purpose, an evaporator side on the one hand and a condenser side on the other hand, as is shown exemplarily by the heat pump 100 in FIG. 5. The heat pump is coupled to a heat exchanger 102 on the evaporator side and a heat exchanger 104 on the condenser side. For this purpose, the heat pump 100 in particular includes an evaporator inlet 101a and an evaporator outlet 101b. Above that, the heat pump 100 comprises a condenser inlet 103a and a condenser outlet 103b. The operating liquid on the evaporator side is introduced into the evaporator of the heat pump 100 via the evaporator inlet 101a, cooled there and let out from the evaporator outlet 101b as colder operating liquid. At the same time, as shown in FIG. 5, the evaporator inlet 101a and the evaporator outlet 101b are coupled to the heat exchanger 102, such that a hotter operating liquid (having the temperature t) is fed into the heat exchanger, cooled in the heat exchanger and then transported to the region to be cooled. Typical temperature ratios are shown in FIG. 5, wherein a “heat exchanger loss” of 1° Celsius is assumed. In particular, t is, e.g., the set temperature in the region to be cooled.
The heat exchanger 102 or 104 has a primary side directed towards the heat pump and a secondary side facing away from the heat pump, i.e. to the region to be cooled or the region to be heated. The primary side of the heat exchanger 102 includes the hot terminal 101a and the cold terminal 101b, wherein “hot” and “cold” are to be seen as terms, and wherein the medium is hotter in terminal 101a than in terminal 101b. Accordingly, the hot terminal of the primary side of the heat exchanger 104 is the terminal 103b, and the cold terminal is the terminal 103a. On the secondary side of the heat exchangers 102 or 104, the hot terminal is in each case the top terminal and the cold terminal is in each case the bottom terminal in FIG. 5.
On the condenser side of the heat pump 100, the condenser outlet 103b is connected to the “hot” terminal of the heat exchanger 104, and the condenser inlet is connected to the colder end of the heat exchanger 104. Above that, on its other side facing away from the heat pump 100, the heat exchanger is connected to the region to be heated, where a set temperature T should prevail.
If the heat pump is used as a cooling unit, the region to be cooled will, so to speak, be the “effective side”. The region to be cooled can, for example, be an indoor room, such as a computer room or another room to be cooled or air-conditioned. Then, the region to be heated would, for example, be the outside wall of a building or a rooftop or another region into which waste heat is to be introduced. If, however, the heat pump 100 is used as heating, the region to be heated will, so to speak, be the “effective side” and the region to be cooled would, for example, be soil, ground water or the like.
In such heat pump applications as shown in FIG. 5, it is problematic that the configuration does not take into consideration that the ambient temperature of the region to be heated, when the same is, for example, outdoors, varies heavily. In winter, temperatures of −20° Celsius can prevail, and in summer temperatures of over 30° Celsius. If, for example, an application is considered where a computer room is air-conditioned, it would be sufficient, for the case that the ambient temperature is, e.g., in the range of or below the set temperature in the region to be cooled, to no longer air-condition the computer room at all, but to simply “open the windows”. This is, however, problematic, since computer rooms do not necessarily have windows and because, at the same time when such cooling is considered, it is relatively difficult to check that there is a constant temperature in the room, because of the fact that particularly cold zones might possibly form close to the windows, if there are any, while further away from the windows or behind specific racks hot zones form that might not be sufficiently cooled. On the other hand, it is problematic in that, in a heat pump configuration such as is illustrated in FIG. 5, the fact that the ambient temperatures can vary heavily and in particular frequently lie within ranges where cooling is normally not necessitated, is not put to effective use. For that reason, a configuration as illustrated in FIG. 5 is implemented for the worst-case situation, i.e. for example for a very hot summer day, although such a hot summer day is, on average, very rare, at least in Germany, and the main part of the time within one year has temperatures where the cooling capacity that may be used is far below the requested worst-case situation.